Automatic telegraph key



March 1948. F. A. BARTLETT 2,437,497

I AUTOMATIC TELEGRAPH KEY Filed Kay 30, 1944 Fa/resi A. Barthel!INVENTOR.

ATTORNEY.

Patented Mar. 9, 1948 UNITED STATES PATENT OFFICE 6 Claims.

This invention relates to electric telegraph apparatus and especially toa transmitter key which is arranged automatically to send a series ofdots or a series of dashes while the key is held by the operator on oneside or the other, respectively, of the silent position.

My invention particularly relates to an improved fully automatictelegraph transmitter key unit which may readily be incorporated in anyradio telegraph transmission circuit and which includes adjustmentsaffording an unusual degree of adaptability to a variety of conditionsof use.

An object of my invention is to provide a small self-containedtransmitter key unit of the character described and of the typeemploying a side-swinging key lever, and which may be operated by anysuitable source of electrical energy of substantially constant voltage.

A further object of my invention is to provide a self-containedtransmitter key unit, fully automatic in operation, which may readily beincorporated in any transmitter set.

A further object of my invention is to provide a fully automatictelegraph transmitter key unit having means to vary the speed of sendingwithin wide limits.

A further object of the invention is to provide a fully automatictelegraph transmitter key unit having means to adjust thecharacteristics of the impulses transmitted, i. e., having means toadjust the speed of the impulses transmitted, as well as the spacingbetween impulses and the relation existing between the length of thedots and the length of the dashes.

Further features of the invention willhereinafter appear in thespecification following and will be pointed out specifically in theappended claims. The invention is herein described and illustrated withreference to specific embodiment illustrated and described by way ofexample only, but the scope of the invention is not in any way limitedto the described embodiment except insofar as defined by the claims.

Referring to the drawings the single figure is a schematic diagram of asimplified electrical circuit for a fully automatic telegraphtransmitter key unit embodying the principles of the present invention'In the circuit illustrated the basic elements of my full automatic keyunit are illustrated diagrammatically and comprise a transmitter keyunit SW1, a relay Ry, and a pair of condensers C1 and C2. The condenserC2 has a capacity materially greater than that of the condenser C1 andboth condensers C1 and C2 are connected in series with each other, andboth condensers are also connected in series as by a circuit l with thecoil 2 of the relay By. This circuit 1 is connected across both poles 3and A of a suitable source of electrical energy E.

The key unit SW1 is preferably of the single pole, double throw type,its blade 5 being mounted for movement to either side of its silentposition so that it can make engagement optionally with either of twocontacts a or b. Another double throw switch SW2 has its blade 6operably connected to the armature a of the relay By in such a mannerthat when the coil 2 is energized, the blade 5 makes engagement with thecontact e, whereas, when the coil 2 is tie-energized the spring 1 of anadjustable tensioning device T draws the blade 6 away from the contact eand into engagement with a contact f. The switch contact f is carried byan adjustment screw 8 whereby the length of stroke of the blade 6 caneasily be varied.

Since the pole 4 of the source of energy E is grounded as indicated at9, the fact that the armature A is connected as by a conductor II to thepole 4 results in permanently grounding of blade 6 of the switch SW2.

The contact e of the switch SW2 is connected as by a conductor l2 to neof the terminals l3 by means of which my improved transmitter key unitcan be connected at the external circuit M to be keyed; the otherterminal 5 being grounded as indicated at H.

The adjustable contact 1 of the switch SW2 is connected as by aconductor 2| which includes suitable resistance R1 to the blade 5 of theswitch SW1. The switch contact a is connected as by conductor 22 withthe conductor l between the coil 2 and the pair of condensers C1 and C2,whereas another conductor 23 connects the switch contact I) to thecircuit I between the two condensers C1 and C2. However, a variableresistance R2 is shunted around the condenser C1 so that switch contactb is always connected to the circuit 1 between condenser C1 and the coil2.

When key unit SW1 is actuated by making engagement between the blade 5and the contact a, the following circuit will be completed, to wit: thepole 3, coil 2, conductor 22, switch contact a, blade 5, conductor 2|including resistance R1, adjustable switch contact I and blade 6 of theswitch SW2, conductor II, and pole 4. Consequently, this circuitoperates to shunt the two condensers C1 and C2 out of the circuit l. The

3 series combination C102 is effectively discharged by virtue of theshort circuit established around the condensers by closing of the switchcontact :1. However, since the circuit which is completed by closing thecontact a results in energizing the coil 2 of the relay Ry, the armatureA will immediately be attracted, drawing the blade 6 away from thecontact f and into engagement with the contact e, thus closing theexternal circuit l4. By moving the blade 6 away from the contact f, thecircuit including the contact a is broken, thus breaking the shortcircuit around the series condenser combination C102, thusre-establishing the circuit 1 which includes the capacity combinationC102 with the result that the condensers will charge at a ratedetermined by their respective capacity. Accordingly, current willcontinue to flow through the coil 2 at a rate which greatly decreases asthe charge of the capacity combination C102 builds up. Obviously,therefore, the

magnetic force exerted by the coil 2 will, after the elapse of a perioddetermined by the total value of the condenser combination CiCz, reach apoint where it is overcome by the tension in the spring 7, whereupon theblade 6 will again be retracted from the contact e and into engagementwith the contact I, thus breaking the external circuit andre-establishing the circuit which includes the contact a, it beingassumed, of course, that the blade 5 has been held closed. This cycle ofevents, therefore, will be repeated continuously as long as the blade 5is held in engagement with the contact a. The periodicity at which theexternal circuit is will be closed will be varied by the tensioningdevice T whereby the tension in the spring I may be adjusted.

'Ihe greater the tension, of course, the lesser will be the delayrequired before the force of the spring is able to overcome the magneticattraction of the coil 2 and correspondingly the duration of closing theexternal'circuit it will be decreased. On the other hand, by variationof the position of the adjustable contact the distance through which theblade 6 travels in moving from the contact e to the contact I can bevaried, with the result that the interval between periods of closing ofthe external circuit Hi can similarly be varied.

When the blade 5 of the switch SW1 is moved into engagement with theswitch contact I), the circuit which includes the variable resistance R2will be completed again, thus causing energization of the coil 2. Whenthe switch blade 5 is moved into engagement with the switch contact I),the following circuit will be completed, to wit: pole 3, coil 2,resistance R2, conductor 23, switch contact 2), blade 5, conductor 2!including resistor R, contact 5 and blade 6, conductor H and pole 3.Therefore, the shunting eiiect produced by closing the contact 22 is thesame as the previously described resulting in energizing coil 2, butwith'the exception that condenser C2 is completely shunted out whereasthe condenser C1 is shunted out only to the extent determined by thevalue of the resistance R2. pacity of a condenser acting singly isgreater than that of a series condenser combination, the effect ofshunting the condenser C1 out of the circuit by the resistance R'z'is toincrease the total condenser capacity'of the circuit and similarly toincrease the length of time required for that total condenser capacityto build up. Therefore, a greater length of time will be required forthe spring I to overcomethe magnetic attraction of Since the efiectiveca- 7 the coil 2 to withdraw the blade 6 from the contact e, with theresult that the external circuit is will be closed for a period ofreater duration than that resulting from engagement of the blade 5 withthe contact a. However, these impulses of greater duration will berepeated in the external circuit [4 as long as the blade 5 remains inengagement with the contact I) just as in the previously describedoperation involving the use of the contact a.

7 Thus it may be seen that so long as the switch blade 5 is kept inengagement with the contact a, a series of impulses of relatively shortduration, i. e,, dots, will be transmitted to the external circuit it;whereas, so long as the blade 5 is kept in engagement with the contacte, a series of impulses of greater duration, 1. e., dashes, will betransmitted to the external circuit M.

The ratio of ldot length to dash length is subject to variation bymanipulation of the variable resistance R2.

I claim:

1. In an automatic telegraph transmitter key, a plurality of condensers,a conductor interconnecting said condensers, a relay comprising a,solenoid, an armature cooperatively associated therewith, a pair ofspaced contacts, a switch blade actuated by said armature to engage oneof said contacts when said solenoid is energized, and spring means formoving said blade into the other of said contacts when said solenoid isde-energized, a conductor connecting said blade to one potential of acurrent source, a conductor connecting one terminal of said solenoid tothe other potential of said current source, a conductor connectin theother terminal of said solenoid to one of said condensers, a keycomprising a blade and a pair of key contacts optionally engaged by saidkeys blade, a conductor connecting one of said keys contacts to saidconductor inter-connecting said condensers'a conductor connecting theother of said keys contacts with said conductor connecting said solenoidto said condensers, a conductor connecting said keys blade to one ofsaid relays contacts, and means connecting the other of said relaycontacts into an external circuit.

2. In an automatic telegraph transmitter key, a plurality of condensers,a conductor interconnecting said condensers, a relay comprising asolenoid, an armature'cooperatively associated therewith, a pair ofspaced contacts, a switch blade actuated by said armature to engage oneof said contacts when said solenoid is ener ized, spring means formoving said blade into the other of said contacts when said solenoid isde-energized, and

' means for varying the force of said spring, a'c'onductor connectingsaid blade to one potential of a current source, a conductor connectingone terminal of said solenoid to the other potential of said currentsource, a conductor connecting the other terminal of said solenoid'toone of said condensers, a key comprising a blade and a' pair of keycontacts optionally engaged by said keys blade, a conductor connectingone of said keys contacts to said conductor interconnecting saidcondensers, a conductor connecting the other of said keys contacts withsaid conductor connecting said solenoidto said condensers, a conductorconnecting said keys blade to one of said relays'contacts, and meansconnecting the other 'of said relay contacts into an external circuit.

3. 'In an automatic telegraph transmitter key, a plurality ofcondensers, a conductor interconnecting said condensers, a relay'comprisinga solenoid, an armature cooperatively associatedtherewith,-a

pair of spaced contacts, a switch blade actuated by said armature toengage one of said contacts when said solenoid is energized, springmeans for moving said blade into the other of said contacts when saidsolenoid is de-energized, means for moving said other of said contactsto vary the distance traversed by said blade in making a contacttherewith, a conductor connecting said blade to one potential of acurrent source, a conductor connecting one terminal of said solenoid tothe other potential of said current source, a conductor connecting theother terminal of said solenoid to one of said condensers, a keycomprising a blade and a pair of key contacts optionally engaged by saidkeys blade, a conductor connecting one of said keys contacts to saidconductor interconnecting said condensers, a conductor connec ing theother of said keys contacts with said conductor connecting said solenoidto said condensers, a conductor connecting said keys blade to one ofsaid relays contacts, and means connecting the other of said relaycontacts into an external circuit.

4. In an automatic telegraph transmitter key, a plurality of condensers,a conductor interconnecting said condensers, a relay comprising asolenoid, an armature cooperatively associated therewith, a pair ofspaced contacts, a switch blade actuated by said armature to engage oneof said contacts when said solenoid is energized, and spring means formoving said blade into the other of said contacts when said solenoid isdeenergized, a conductor connecting said blade to one potential of acurrent source, a conductor connecting one terminal of said solenoid tothe other potential 01 said current source, a conductor connecting theother terminal of said solenoid to one of said condensers, a keycomprising a blade and a pair of key contacts optionally engaged by saidkeys blade, a conductor connecting one of said keys contacts to saidconductor interconnecting said condensers, a conductor connecting theother of said keys contacts with said conductor connecting said solenoidto said condensers, a conductor connecting said keys blade to one ofsaid relays contacts, a resistor, means connecting one terminal thereofto said other terminal of said solenoid, means connecting the otherterminal of said resistor to said conductor interconnecting saidcondensers, and means connecting the other of said relay contacts intoan external circuit.

5. In an automatic telegraph transmitter key, a plurality of condensers,a conductor interconnecting said condensers, a relay comprising asolenoid, an armature cooperatively associated therewith, a pair ofspaced contacts, a switch blade actuated by said armature to engage oneof said contacts when said solenoid is energized, and spring means formoving said blade into the other 01 said contacts when said solenoid isdeenergized, a conductor connecting said blade to one potential of acurrent source, a conductor connecting one terminal of said solenoid tothe other potential of said current source, a conductor connecting theother terminal of said solenoid to one of said condensers, a keycomprising a blade and a pair of key contacts optionally engaged by saidkeys blade, a conductor connecting one of said keys contacts to saidconductor interconnecting said condensers, a conductor connecting theother of said keys contacts with said conductor connecting said solenoidto said condensers, a conductor connecting said keys blade to one ofsaid relays contacts, a variable resistor, means connecting one terminalthereof to said other terminal of said solenoid, means connecting theother terminal of said resistor to said conductor interconnecting saidcondensers, and means connecting the other of said relay contacts intoan external circuit.

6. In an automatic telegraph transmitter key, a plurality of condensers,a conductor interconnecting said condensers, a relay comprising asolenoid, an armature cooperatively associated therewith, a pair ofspaced contacts, a switch blade actuated by said armature to engage oneof said contacts when said solenoid is energized, spring means formoving said blade into the other of said contacts when said solenoid isde-energized, and means for varying the force of said spring, aconductor connecting said blade to one potential of a current source, aconductor connecting one terminal of said solenoid to the otherpotential of said current source, a conductor connecting the otherterminal of said solenoid to one of said condensers, a key comprising ablade and a pair of key contacts optionally engaged by said keys blade,a conductor connecting one of said keys contacts to said conductorinterconnecting said condensers, a conductor connecting the other ofsaid keys contacts with said conductor connecting said solenoid to saidcondensers, a conductor connecting said keys blade to one of said relayscontacts, a variable resistor, means connecting one terminal thereoi tosaid other terminal of said solenoid, means connecting the otherterminal of said resistor to said conductor interconnecting saidcondensers, and means connecting the other of said relay contacts intoan external circuit.

FORREST A. BARTLETT.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,928,967 Gilbert Oct. 3, 19332,235,627 Boor Mar. 18, 1941 2,302,290 Breedlove Nov. 17, 1942 2,303,734Garceau Dec. 1, 1942

